The Signature Killer
by whomaniac
Summary: Post-Reichenbach. Sherlock is gone. John's mind has gone as well, and that doesn't bode well for the people of London when John becomes a serial killer because of his rage and his insanity.


**Hey everybody! New Story time! YAY! A Post-Reichenbach one, in which John has gone mad without Sherlock. Dark!John. Some Johnlock. Angst. Lots of it. And sexual assault toward the end... but nothing graphic. ENJOY!  
****Disclaimer: I own nothing. Nothing at all save for my insanity and mediocre writing skills. ;) **

"_That's what people do don't they, leave a note?" _

"_Leave a note when?"_

"_Goodbye, John." _

"_No—don't." _

He remembered it all too well. The falling. Watching his friend tumble to his death and not being able to do a damn thing to save him. Sherlock, goodness it pained John to even think of his name, was gone. For all intents and purposes he had given up on life. He'd given up on John.

John didn't believe a word of his rubbish about being a fraud, about inventing the consulting criminal, about any of it. He never would believe it. Only one man could be that clever. And that was… him.

John felt himself grow angry for the umpteenth time that morning and he threw the knife down on the ground, the blood spilled all over his hands from yet another victim. He didn't know their name and he didn't care. Remembering names caused him too much pain. And he'd grown past the point of caring. His best friend was dead. He had nothing left to live for.

* * *

It hadn't always been like this. John would occasionally, and fondly, remember the good old days when he and the detective would still solve crimes together. He remembered the blog, long since abandoned. Many happy returns… that was the last thing he'd ever gotten from Sherlock. A rubbish birthday video with a wink and a smile saying he'd see him soon.

IT WAS ALL LIES.

John mentally kicked himself for side tracking from trying to cheer himself up. He'd gotten away with so many killings, and being on the lam was one hell of a thrill. Soon he'd get even more unwanted attention, and he'd start going after the people he used to hold most dear.

The woman he almost married had been the first one to go. He growled to himself delightfully at the thought… she bloody deserved it for trying to replace… him… so soon. That was the only victim he knew the name of. But that would soon change. All of them would have to go because if he had to live without him, they couldn't live at all.

John Watson had changed. And not for the better. Two years had passed since that fateful day at St. Bart's. His mind was warped past all normal function. He'd turned. If London thought Moriarty was a worthy adversary, they had another thing coming. And he was just getting started.

John growled to himself, walking over to the table and picked up another knife with a gloved hand. He ran a finger down the blade, holding it up to the light and watching as the beams glinted off the steel. Soon…very soon. His lips curled into a malevolent smirk as he thought of the idea of taking another life. Oh, _he_ would have loved trying to solve these cases. John never left a scrap of evidence. That was the thing about working with a sociopathic consulting detective. You always knew the best way to carry out a murder. And the knife… well that was just a personal touch, with a special signature just for the Yard…

The ex-army soldier had gone insane. He was no longer the John Watson that everyone used to know. The loyal man was gone, and in his place, a monster had arisen. A beast clad in all black that cared about nothing more than the next victim. Because he was a man who had nothing to lose, and there was only satisfaction to be gained in these acts.

* * *

The shaggy, long-haired man dashed through the forest, trying to avoid the guards that were stationed everywhere. However, he'd been discovered. There was no stopping that now. His long legs carried him as fast as he could go, but the guards were advancing. The man heard the noise of a helicopter above him and soon, a spotlight being shone right on his back. He heard the cocking of guns and his chest heaved, breathless. He dropped to his knees and remembered only the ground reaching out to meet him.

He came back to his senses in a dimly lit prison cell. It was obvious it was in an underground bunker; the moisture that seeped throughout it and the plumbing and wiring that were visible gave that away. The door was locked shut. Not that that mattered. His limbs were pulled taut at his sides by the manacles around his wrists, his bare upper half shone with a glint of sweat from the exertion. He felt nothing but pain as his captor delivered blow after blow to his body while his apparent supervisor in the green over coat merely sat and watched. He didn't give them any satisfaction. He bit back the cries of pain.

As they continued questioning him, he merely deduced that the man's wife was cheating on him with the coffin maker next door, and that if he headed home now he would catch them at it. The man-made a beeline for the door, tossing his makeshift beating stick, which happened to be a lead pipe, aside. The green coat man spoke a few words, before getting to his feet and deciding to grab a handful of the fake hair that covered the man's head. "Now listen to me." Mycroft Holmes snarled in the ear. "There is something new back in London. It's dangerous. And you're needed. Sorry, but the holiday is over. Back to Baker Street, Sherlock Holmes." He sneered the name, and his younger brother didn't move a muscle, except for the slightest twitch of his lips in a smirk.

* * *

John Watson kept the knife in the pocket of his leather jacket. He was waiting for the most opportune time to find an unsuspecting victim. London was a great cesspool of victims. He need only find the right one, the most desirable one. He growled under his breath as anyone made eye contact with him. He had developed both sociopathic and psychopathic tendencies, and all people repelled him. One in particular, but he was safe because he was dead. Or so John thought.

* * *

Sherlock Holmes, now completely devoid of all disguises, had just returned to his brother's office and was getting his face shaved at the time, sighed. "So, what is 'new' that you think is so interesting? I was in the middle of something."

"A small thank you wouldn't go amiss."

"For what?"

"I got you out!"

"I got me out."

Mycroft kept calm, no matter how much he wanted to slam his brother's face into a wall. Sherlock sat up, brushing away from the person shaving his face. "Well?"

"It's… complicated, Sherlock. A serial killer. Only his patterns constantly differ. The only thing that is similar every time is the signature he leaves upon the victim's bodies." Sherlock got to his feet, wincing from near on being beaten to a pulp. He walked to his brother's desk, eyebrow piqued. It was intriguing.

Mycroft glanced at him. Sherlock rolled his eyes. "What is the signature?"

His older brother handed him a folder full of case files and photographs. Sherlock shuffled through it meaninglessly. "Curious. SH? My initials. What else is interesting about this though? It's clearly an attention getter. My attention at that."

Mycroft rolled his eyes this time. "Obviously, brother dear. They just discovered another body last night. Lestrade has the details. He doesn't know you've returned."

Sherlock didn't care about Lestrade. There was only person he was concerned with as of now. "And John Watson?"

"John?"

"Where is he? How is he?"

Mycroft almost handed over another file, but he stopped. Sherlock deduced the action as hesitant and was confused as to why. He held out a hand and snarled a little when Mycroft pulled it away from him. "About that…"

"What?!" Sherlock snapped. Mycroft sighed, pinching the bridge of his nose.

"The situation… involves him."

Sherlock immediately thought the worst. "Is John dead?"

"No! Although, it would be better if he were." Mycroft felt no remorse in saying it. It was true after all.

Sherlock snarled at him. "Mycroft! How dare you!"

The elder Holmes sighed again. "Sherlock… all I'm saying is that John is alive. He is unwell. Your 'death' caused him to go mad. He is the serial killer I am referring to."

Sherlock went silent for a long while, placing the case file on the desk. John? His John, a serial killer? Certainly not… he had a temper, and he wasn't a major people person. But he would never kill anyone unless he _had_ to. He was a solider for god's sake! His thoughts raced for reasons why. Sherlock had to fake his death; else John wouldn't have even lived to see the light of another day. And then he had to lay low and dismantle Moriarty's web. But John… John hadn't taken it well. "Two victims... no, three. You said there'd been another one."

Sherlock felt his eyes mist with tears and he immediately fought them back. Emotions caused mistakes. Just treat it as another case. Cross that bridge when they got to it, and probably burn it in the process. "Mycroft, you have been keeping tabs on him. Where is he?"

"Sherlock you can't just go barging in. It's not John anymore. There's nothing left of the man you once called your friend." Mycroft insisted. His little brother needed to see reason.

He was more than a friend, Sherlock thought to himself. "But surely if he realized that I'm still around, he'd stop it all?"

Mycroft scoffed. "Self-centered much, brother mine? No, we have to be sensible about this. You have to act like you don't know it is John. You have to take care of this, Sherlock. Once and for all. He's killed too many people, and he is making quite a mess that _I_ have to clean up."

Sherlock wasn't listening to his brother's complaints. He knew that he could get John to see reason. He just knew. Sherlock was the only one who could even get close to him… he'd have to try.

* * *

John had a new plan this time. Oh yes, the chloroform soaked cloth was ready in his hand. He'd take the victim back to his place for an... experiment of sorts before carving their guts with the usual message. He growled to himself as he noticed a familiar looking stature nearby. Black curls, tall and lean. Their back was turned, and he couldn't tell, but even the slightest resemblance to that heinous man-made John seethe with rage. That would be his next victim. John would wait for the man to walk outside… be alone. Yes, that was the most opportune time to do such a thing. All he had to do was wait. John walked up to the bar and grumbled to the barkeeper to give him a pint. Might as well use the time he had.

John sipped the beer, tossing a note in the bartender's direction. He kept a watchful eye on the curly-haired man, his eyes constantly scanning the room for other potential problems. And problem it was; because forget the man who looked like that bastard, the real thing had just walked in the door. The incandescent eyes, the unruly curls, the lanky body that was as skinny as a rake, and those cheekbones… those god damned cheekbones that were so high and so sharp… John felt himself losing focus and he growled, rage replacing other emotions that tried to make themselves known.

Sherlock Holmes, it didn't hurt to think it anymore when John realized he was still alive. Immediately he was overwrought by more anger.

HOW WAS HE ALIVE. HE JUMPED OFF A BLOODY BUILDING.

John shook his head and finished his pint before heading to the washroom. He glanced at his hands. God, how he had changed. The tremor is his left hand was gone, he was constantly under stress and duress and he fucking loved it. The thrill of the chase, the blood pumping through his veins as he hunted out his victim. He chuckled to himself at the change he'd made to his old _friend's_ saying. When he came back out, Sherlock had moved to the bar. The man didn't drink and John knew that. Well, he seldom drank. And apparently this was one of those opportune moments, for Holmes was ordering a pint and nursing apparent alcoholism. Or so it seemed.

John casually flattened his hair and strode to the bar, taking the stool next to the detective. He didn't glance over, and he didn't move. He only ordered a pint in a Scottish accent. Surely the genius would have noticed him by now. He had to have noticed him. This was Sherlock Holmes he was dealing with, and not some average Scotland Yard idiot.

John waited. His brilliance was all a waiting game. Perfect timing and planning were a must. He fished what he needed out of his pocket, a small pill that when dropped into the detective's drink… oh the detective would be rambling on and on about god knows what and he would be vulnerable. And John would have his revenge. It was almost too simple.

Sherlock turned for a moment, taking one sip before setting the glass aside. John quickly slipped the drug into the amber liquid and watched it dissolve. He quickly put it back where Sherlock had placed it and ducked away from the bar again. With any luck, Sherlock would start rambling and get thrown out in at least three minutes.

John almost laughed to himself as he watched the man become slowly more deterred and confused. He knew the detective couldn't retain liquor very well, but even this was pushing it. However, as Sherlock's rambling became more and more rowdy the bartender told him to get out, and Sherlock stumbled to the door. The drugs were clearly having and effect and John smiled again. He ran his fingers over the weapon in his hand. Soon… but he'd have his fun with this one first. This one had caused him all the pain, and he was going to do the same to him: Sherlock Holmes.

Sherlock staggered outside, struggling to stay on his feet. The alcohol was stronger than usual apparently. His motor skills were clearly lacking, that was why he never drank. It postponed and sometimes even dulled out thinking completely. And this was one of those times.

John decided to put on the accent again, just for fun. "Oi mate! Need some help keepin' upright?" He laughed and generously offered Sherlock a shoulder to lean on.

"Th-thanks…" Sherlock slurred, practically throwing his weight against John. It sent the other man tumbling sideways, but he caught Sherlock and Holmes met eyes with him for a moment. He swore and shoved him alongside him as he walked. "Let's get you home, yeah?"

Sherlock nodded. "Yes, Jawn…" John smirked to himself. Oh he was going to enjoy this.

* * *

Sherlock came to, and every part of his body ached. It felt worse than the time in Serbia. He looked around himself. Piles of pallets were everywhere. A warehouse then. It was dark, but there was a small table illuminated in front of him. It was blurry, and he blinked a few times to clear up the vision. A man sat at the table, a cruel look on his face. Sherlock narrowed his eyes and then they suddenly widened. Of course it was John. He was about to speak but found it incredibly difficult. And then he realized why, his mouth was gagged. Further observation showed that his arms were tied behind him. He was tied to a chair and John Watson was sitting across from him. Any other time it would have been kinky, but this was not the John Watson he knew.

The black-clad man sneered at Sherlock. "That's all it took to beat you, Holmes. A drug in a beer and a Scottish accent. My you can tell you're slipping." John laughed at his own wit before tearing the gag off Sherlock's mouth. Sherlock looked up at him, a pained expression on his face. "John…"

Watson laughed again. It was a maniacal laugh and it frightened Sherlock to see him like this. "Oh _Sherlock_! You finally come back! Bet this wasn't what you were expecting was it! When your big brother told you a big bad man was wreaking havoc in London. You certainly didn't expect wee little John Watson to be behind it all. No, John Watson isn't capable of that. The soldier boy, he wouldn't harm a flea unless that flea harmed his Sherlock first." Another laugh escaped him and he stared at the detective.

"I always figured you were still alive. The first few months, I held onto the hope that I hadn't lost you. But now I don't care. What I do care about… is how this knife is going to look when it carves through that delightful alabaster flesh…" He brandished the knife in Sherlock's direction, snarling in delight.

As John went on and on, Sherlock actually became more and more afraid. He tried to loosen the bonds on his hands, but they were held fast just like his ankles. Holmes finally spoke, "You know, the fact that you thought one tiny little drug would affect me so much only proves my point. You always did lack in the brain department, Watson. Then again, everyone does. It's called acting, John."

John pointed the knife at him in a mocking manner. "Oh, except you of course. Because you're a flawless genius junkie. Is that it?"

Sherlock scoffed. He hated this. He hated seeing John this way. "Flawless? Heavens no. Genius? I like to think so. Junkie? Not in awhile. But being one back in the day helped me build immunity to certain date rape drugs, Watson. Even you, as a medical man would know that."

"Ha! You still think I'm a doctor. Sure… I'll fix all your wounds right after I create them, Sherlock Holmes. And then we can start _allllllllll_ over." He slammed his hands down on the table and snarled. "You aren't getting out of this one, Holmes. There's no one around to hear you scream. Except me. And I'll be looking forward to every. Single. One." John stared up at him and got to his feet, throwing the table out of the way in rage and storming over to Sherlock. The detective slunk away slightly. The knife appeared in one of John's hands and was right next to Sherlock's face.

"Now… how shall we begin…"

Sherlock's eyes were pleading for the real John Watson to appear out of this monstrosity sometime soon, but he a feeling that wasn't going to happen. As the knife hovered next to his cheek, he stared down the man before him. "John, stop… this isn't you."

John laughed and crouched down enough to be in his face. "Sherlock, you did this to me. I waited. And waited. I thought you were dead. I had nothing else to live for. So I finally said to hell with it and I began plotting. Oh, how I plotted. You have no idea what I have done, Sherlock. Two years of planning…" John licked his lips in a savory yet insane manner. "It took me longer than it would have taken your brilliant mind, sure. But I did it. What was the one way to get you to come back from the dead? What would get you to come back and play? Eh, being a serial killer? 'The game is on, Sherly…' And nothing you do will stop what I am about to do to you." He pressed the blade against Sherlock's face.

Sherlock felt the metal cut into his skin. He felt heat on the wound, blood slowly dripping out of the scratch. He ignored it. "John… I was trying to protect you. I did it _for_ you."

John laughed. "By leaving me alone with nothing for two years! I think it's a bit late for protection, Sherlock!" He growled, moving the knife upward slightly to get a new angle for another cut. Sherlock winced, and John seethed with maniacal delight.

"John these detrimental effects can be reversed. Don't do this…" Sherlock winced as yet another cut was made. John stopped for a minute.

"You think I wanted to be like this Sherlock? Do you actually think I did this on purpose? No, this is because of you. I was left alone to slowly go mad, and this is what it led to."

This called for desperate measures. John needed to be shocked right out of this madness. Luckily he'd never claimed his feelings for the man before. He doubted John felt the same way anyhow. Sherlock glanced at him. "I know this isn't you John, please. This isn't the John Watson I fell in love with…"

That made John stop. The grip on the knife slackened, his hand falling to his side as he took a few steps. His back was turned to the detective, and his thoughts were reeling. 'He's lying. He doesn't feel that way. He never has. There was never anything there. He doesn't feel things that way.' And yet, 'He just confessed to being in love with me! Sherlock Holmes, with me! Ha! I knew he felt the same! I just knew it!' And John suppressed those feelings right then and there. He wasn't that man anymore. He'd never be that John Watson again. John turned to face the detective once more. "Enough of your lies. I should just kill you now… but there's no fun in that. Not when there's so much left to do…"

Sherlock didn't want to beg, but he had to do something. "Please John!" Nothing. The man came closer, the knife raised again. "Please…" He choked back a sob.

"Oh for heaven's sake… you're crying? Christ, Sherlock. Learn to take it like a man…" John laughed to himself again. "Actually… you know what, I have a different idea."

Sherlock glanced up, trying to read his intentions, but he didn't have time for that. He felt his head being jerked upward and suddenly his lips were being assaulted by more lips and he didn't know what to do but he wanted this so badly, but this wasn't his John. It was wrong. He pulled away, but the cruel man only pressured on, keeping Sherlock right where he wanted him. Sherlock whimpered softly and John let up. There was a different glint in his eyes. A glint of lust. Sherlock knew what was going to happen now, and he was terrified. "John! Stop! Please I know that you're still in there somewhere… you can't be gone completely…"

"Sorry, Sherlock… but I am." With that, John's kisses started wandering down to Sherlock's neck, and Sherlock didn't want to fight back but at the same time he did. He grabbed a handful of the black curls and pulled them while he kissed, causing Sherlock to yelp in pain. Mm, he loved making Sherlock make those noises.

"I'm not going to kill you just yet, _love._ First, I have something special in mind!" Sherlock's eyes widened as his shirt was suddenly torn open, buttons clicking against the concrete floor. John's hands touched his bare flesh and he shuddered, but it wasn't all bad.

Deep down, there was more to this than what John was cruelly enjoying. There was some… spark that hadn't been there before. He tried to suppress it but it just kept getting bigger and bigger. His hands wandered up and down Sherlock's chest, feeling out every inch of him. His insane smile grew as his kisses turned into playful bites, and Sherlock tried to pull away from him.

Finally, that spark caused something within John's deranged mind to snap. All of the black thoughts, the dark, brooding nature of his thoughts that had haunted the depths of his mind for two years had finally ceased to exist. He closed his eyes for a moment, his hands against Sherlock's chest as he stopped moving. When he opened them again, he saw the detective in an entirely new light. "Sherlock…" His voice wasn't gravelly. It wasn't degrading. It was just a light, soft tone now. It was John's voice.

Holmes glanced at him as he stopped, confused. "Get it over with then. I thought you were going to kill me. Well come on then, do it!" Sherlock shouted at him, growling afterward.

John glanced at the knife in his hand and then at the cuts on Sherlock's face. The weapon slowly slipped through his fingers and clattered to the floor. "Sh-Sherlock… oh my, oh dear god…"

Sherlock glanced at him. He looked him over. John wasn't bloodthirsty, murderous. He just looked like John. His expression was soft, yet structured. Military. It was _his_ John. Sherlock had done it. He'd fixed him. Well… more or less. Now he was a quivering mess and he couldn't stop shaking. "John…" Before he knew there were arms being thrown around him and squeezing him to the point of suffocation.

"Sherlock you bastard, I thought you were dead. I'm… I'm so sorry.. I lost control. I couldn't take it. I watched you fall off the rooftop. I watched you fall to your death…" John quickly untied Sherlock and slumped to his knees, shaking and shuddering in despair. He had hurt Sherlock just because Sherlock had hurt him. He felt tears prick his eyes, and he soon felt arms around him. "John… John I'm here… I'm never leaving again…"

John didn't reply. He buried his face in Sherlock's neck and cried. Sherlock thought this was insane, but this was clearly his John. He winced at the pain in his face but he just stayed there and held John. Eventually the small man calmed down, his shuddering had stopped.

"John, I'm.. uh… not dead."

"No shit, Sherlock. Shut up or you might be."

Sherlock chuckled softly. "But John… I have just one question. Before you were about to… well, those feelings that I confessed to…"

"Didn't I just tell you to shut up?" He hauled Sherlock into another kiss and they stayed there like that for a while before John ended it. "Of course, Sherlock. I've always had those feelings, and I am so sorry… I will do whatever it takes to make it up to you."

Sherlock was elated to hear those words, and the kiss. Well the kiss was just bloody fantastic. And there would be a lot more of those in the future. Of course, John had to answer for his crimes, but it did so happen that the men he killed, yes including Mary—she'd been a sniper at the pool—had worked for Moriarty, so that was at least useful in a way. The courts in fact exonerated him for getting rid of high-risk targets, but he was kept under strict surveillance.

* * *

As for Sherlock and John, everything went back to normal. Well, as normal as it could get in 221B. Sherlock got chewed out for faking his death, and John vowed to never kill anyone again. Shame, that probably wouldn't last in their line of work, but John would never go back to that lifestyle. He had his Sherlock, and for once the soldier was at peace.


End file.
